“For all his patriotism, there was nothing in the great man’s words or deeds which suggest he was anything other than a loyal unionist,” he said.

“This matters, particularly as we close in on next month’s referendum and both sides try to win over voters in tonight’s BBC debate between Salmond and Alistair Darling.

“Scott, my great-great-great-great grandfather, did more than anyone else to create the Scotland we know today, with its romance, ubiquitous tartan and unique status within one of the most successful political unions in history.”

He added Mr Salmond’s claim reflected the continuing influence of Sir Walter on the cultural life of Scotland, despite him being a “Tory and an Anglophile”.

Saying he believed Sir Walter would have “invited Salmond to mull the issue” at his home, before writing about it through the eyes of ordinary people.

On the issue of the coming referendum, Mr Scott concluded: “The end could be in sight. It is one neither [former First Minister Donald] Dewar nor Scott wanted.